package xin.nick.util;

import javax.servlet.http.HttpServletRequest;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Objects;

/**
 * ip获取
 * @author Nick
 * @since 2022/1/24
 */
public class IpUtil {

    public final static String UNKNOWN = "unknown";
    public final static String LOCAL_IP = "127.0.0.1";
    public final static int IP_LENGTH = 15;
    public final static String SEPARATOR = ",";

    public static String getIpAddress(HttpServletRequest request) {
        String ipAddress;
        try {
            ipAddress = request.getHeader("x-forwarded-for");
            if (ipAddress == null || ipAddress.length() == 0 || UNKNOWN.equalsIgnoreCase(ipAddress)) {
                ipAddress = request.getHeader("Proxy-Client-IP");
            }
            if (ipAddress == null || ipAddress.length() == 0 || UNKNOWN.equalsIgnoreCase(ipAddress)) {
                ipAddress = request.getHeader("WL-Proxy-Client-IP");
            }
            if (ipAddress == null || ipAddress.length() == 0 || UNKNOWN.equalsIgnoreCase(ipAddress)) {
                ipAddress = request.getRemoteAddr();
                if (LOCAL_IP.equals(ipAddress)) {
                    // 根据网卡取本机配置的IP
                    InetAddress inet = null;
                    try {
                        inet = InetAddress.getLocalHost();
                    } catch (UnknownHostException e) {
                        e.printStackTrace();
                    }
                    if (Objects.nonNull(inet)) {
                        ipAddress = inet.getHostAddress();
                    }

                }
            }
            // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照‘,‘分割
            // "***.***.***.***".length()
            if (ipAddress != null && ipAddress.length() > IP_LENGTH) {
                // = 15
                if (ipAddress.indexOf(SEPARATOR) > 0) {
                    ipAddress = ipAddress.substring(0, ipAddress.indexOf(SEPARATOR));
                }
            }
        } catch (Exception e) {
            ipAddress="";
        }

        return ipAddress;
    }
}